Large quantities of linear alkyl primary amines are presently produced commercially from the natural fatty acids in coconut oil, palm oil, tallow, etc. The market for these amines exceeds 100 MM lbs/yr, with applications in the rubber and detergent industries and as chemical intermediates. This invention concerns the synthesis of linear alkyl primary amines from a petrochemical source, viz, .alpha.-olefins, via an oxoamination process. Said process comprises (a) hydroformylation of linear alkyl .alpha.-olefin substrates to the corresponding straight-chain aldehydes containing one more carbon atom (Eq. 1) and (b) amination of said linear aldehyde to the corresponding desired linear alkyl primary amine (Eq. 2). EQU RCH.dbd.CH.sub.2 +CO+H.sub.2 .fwdarw.RCH.sub.2 --CH.sub.2 --CHO (1) EQU RCH.sub.2 --CH.sub.2 --CHO+NH.sub.3 +H.sub.2 .fwdarw.RCH.sub.2 --CH.sub.2 --CH.sub.2 --NH.sub.2 +H.sub.2 O (2)
After an extensive research program the applicants have developed a class of ligand-stabilized platinum(II)-Group IVB metal halide catalysts for step 1 which as the advantages of:
(1) High selectivity to the linear aldehyde in step 1 with little branched aldehyde contaminant
(2) Ease of separation of the intermediate aldehydes from the platinum catalyst, particularly in the case of dispersions of the ligand-stabilized platinum(II) halide catalyst in quarternary ammonium salts of trichlorostannate(II), without the need to destroy, or precipitate, the catalyst as in analogous, cobalt `Oxo` technology.
(3) Furthermore, said dispersions of ligand-stabilized platinum(II) halide catalysts in quaternary ammonium salts of trichlorostannate(II) remain active after linear aldehyde recovery and may be recycled with fresh .alpha.-olefin charge, thereby achieving additional linear aldehyde syntheses.
The class of oxide-supported nickel-containing catalysts developed by the applicants for step 2, the reductive amination of the linear aldehyde intermediates to linear alkyl primary amines, also have the intrinsic advantages of:
(1) Exhibiting high selectivity to said linear alkyl primary amine with little formation of branched alkyl or secondary amine formation. and
(2) Good specific activity, which allows the reductive amination reaction to be carried out rapidly under moderate conditions of temperature and pressure.